A United Airlines ground stop was lifted yesterday at multiple airports across the United States.

The ground stop impacted major hubs like Chicago O’Hare International Airport for hours, causing long waits and extensive delays for passengers arriving and departing.

United said a “technology issue” prompted them to request the ground stop and hold departures at about 5:12 p.m. CT. They released a statement around 9.00 p.m. CT saying that the issue had been resolved and they were working to get flights moving again.

“We are working with customers to get them to their destinations after a technology disruption on Wednesday evening. The underlying technology issue has been resolved, and, while we expect residual delays, our team is working to restore our normal operations,” the statement read.

The ground stops also impacted major United hubs in Denver, Houston, San Francisco and Newark.

Flights already in the air were able to continue to their destinations, and United Express’ regional flights were not affected, but were delayed going into some of the airports due to a rippling traffic jam effect.

The Federal Aviation Administration released a statement on the issue, writing: “We’re aware United experienced a technology issue disrupting their operations. Some delays may continue as they work through the recovery process. We’ve offered full support to help address their flight backlog and remain in close contact with United.”

United also sent a text message to passengers saying in part, “Due to a technology outage, we are temporarily holding some United flights at their departure airports to manage gate availability at destination airports. This may result in delays throughout the evening as we work to resolve the situation.”